Sealing System for Joints

ABSTRACT

A gasket and seat system for sealing a joint is disclosed. The gasket comprises, for example, an inner portion with a wall facing an interior of the coupling and an outer portion, which extends axially forming radial end walls. The inner portion of the gasket is formed with an angled wall, making the inner portion expand inwards, which angled wall interacts with a matching angled wall of the seat, such that the joint has provisions for increasing the sealing ability in cases with increased pressure in the coupling. The gasket may further have the wall facing the interior being adapted to be flush with an interior surface when mounted in the seat and may also have provisions for heat expansion and elevated pressures, in order to remain flush with the coupling at elevated temperatures and in order to ensure sealing at elevated pressures.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/666,743, filed Jun. 6, 2008, which is a 371 application ofPCT/SE05/01388 filed Sep. 21, 2005.

FIELD

The present invention generally relates to a sealing system forsubstantially immovable joints of two elements, and more specifically toa gasket and seat system for sealing between substantially immovablejoints such as flanges, tube or pipe couplings, housings, shafts, etc.Preferably, the system provides a hygienic sealing with a smooth surfaceto a product provided within the joint elements and which also handlesvolumetric changes in the rubber caused by temperature changes, andpreferably the system provides a sealing that in addition toleratesincreased pressure conditions on the sealing system without degradingits sealing performance.

BACKGROUND

A gasket and seat system of the kind described above is for exampleshown in DE-A-42 01 535. The sealing according to this system willprovide a gasket being flush with the interior surfaces of the pipes andit has some provisions for heat expansion.

Gasket and seat systems that provide gaskets flush-mounted with theinterior surfaces of pipes are for example desired in the pharmaceuticaland food industry. For instance, the ISO 2852 standard of 1993 definesstainless steel pipe couplings for the food industry, wherein a gasketis disclosed as a ring-shaped pipe coupling part intended to make ahygienic liquid-tight joint between the flanges of two clamp liners.This kind of sealing system is intended to prevent residue and bacteriafrom accumulating in pipe joints, especially e.g. in crevices of thesealing system. The pipes of these facilities are regularly cleaned byCIP (Cleaning In Place) and SIP (Sterilization In Place) with hot steam(140 C) in order to kill bacteria that may be present in the pipes. Thismeans that the gaskets must be able to handle heat expansion whileremaining flush, or almost flush, with the interior surfaces of thepipes even during steam washing. If the gaskets project from the pipeinterior, they can further induce turbulence in the pipes and this maybe unwanted in some cases. The gasket disclosed in ISO 2852 does nothave provisions against such expansion into the pipe interior caused bya difference in the expansion coefficients of the pipe material and thegasket material. Furthermore, the same problem applies to other types ofjoints than pipe couplings, having similar sealing purposes, forinstance a heat exchanging system for heating a product inside a pipe.In this case different operating temperatures cause a different amountof expansion during operation. The sealing has to cope with thesevarying operating conditions without causing undesired crevices, asexplained above.

With a gasket and seat system of the known kind, there is no provisionfor improving the sealing ability during periods with increased pressurein the pipes. The gasket inner portion is also rather large, whichincreases the risk of this portion expanding, due to increased heat,into the interior of the pipes. Since the gasket furthermore issymmetrical, machining is necessary in both parts of the coupling inorder to form an appropriate seat. The same problems occur with knowngasket and seat systems for similar couplings, e.g. in pump housings offood pumps.

Hence, there is a need for a more advantageous sealing system.

SUMMARY

It is an object to solve at least the above problems, singly or in anycombination, by arranging a gasket and seat system which provides agasket for a joint, such as a coupling or union of similar elements,such as flanges, tube or pipe couplings, housings, shafts havingattached elements thereto, etc, and which has provisions for increasingthe sealing ability in cases with increased pressure in the joint, suchas a pipe or a coupling.

This object is obtained by the features of the various aspects shown asdefined in the attached claims. Particular embodiments are given in thedependent claims. In an embodiment, the gasket may have a wall facingthe interior being adapted to be flush with an interior surface whenmounted in a seat and may also have provisions for heat expansion, inorder to remain flush with the joint elements, as e.g. a pipe or acoupling, at elevated temperatures. Moreover, a pressure applied on tothe gasket improves the sealing capability of the gasket and seat systemby tightening the gasket using the hydraulic force pressing onto thegasket for improved sealing of the gasket against the counter faces. Thegasket may furthermore be self-retaining inside the seat, whichsimplifies the procedure of coupling the joint elements, e.g. pipes orunion elements. In another embodiment, the seat is only formed in onepart of the joint, e.g. in one pipe or flange, thus reducing the amountof machining necessary. Yet another embodiment may have a silver ioncoating on the gasket for obtaining antiseptic properties.

More particularly, according to one aspect, a gasket and seat systemsuitable for sealing a joint is provided. The gasket may be made of apolymeric material comprising an inner portion, with a wall facing aninterior of the joint, and an outer portion, which extends axiallyforming radial end walls, wherein the inner portion of the gasket isformed with an angled wall, making the inner portion expand inwards,which angled wall is configured to interact with a matching angled wallof the seat.

The wall facing the interior of the joint may be adapted to be flushwith an interior surface of the joint when mounted in the seat, thusproviding a hygienic interior surface not susceptible for contamination.

The wall facing the interior of the joint may be angled slightly inwardsfrom a common point of engagement for the interior surface and the wall.Furthermore, the gasket may be formed with a groove in the outer portionthereof, and may be formed with angled walls of the outer portion whichare compressed upon entry in the seat.

A gasket surface facing a flange plane may be adapted to be flush withthe flange plane after assembly.

The gasket may comprise silver ions, in order to obtain antisepticproperties.

The joint may be a pipe coupling that may comprise two flanges, whereinthe gasket may be located in one of said flanges only, preferablypre-mounted in said one flange during assembly of said system.

The joint may be comprised in a pump housing of a pump for foodprocessing or pharmaceutical product processing. According to a furtheraspect of the invention, a gasket of polymeric material is provided,which gasket is adapted to seal a joint comprising an inner portion,with a wall in use facing an interior of said coupling, and an outerportion, which extends axially forming radial end walls, wherein theinner portion of the gasket is formed with an angled wall, making theinner portion expand inwards, which angled wall is configured tointeract with a matching angled wall of the seat.

The polymeric material of the gasket may be elastic and resilient andmay comprise rubber materials such as EPDM, Viton®, VMQ, FPM, FKM andHNBR, thermoplastic materials, or compositions comprising such materialssingly or in combination.

According to yet a further aspect of the invention, a gasket and seatsystem as mentioned above, according to the above-mentioned aspect ofthe invention, is used for hygienically sealing a joint comprising acoupling in a union of coupling elements adapted for food orpharmaceutical processing. According to another aspect of the invention,a method of assembling a gasket and seat system for sealing a jointaccording to the above-mentioned aspect of the invention is provided.The method comprises pre-mounting the gasket in one element of thejoint, wherein said element comprises said seat, such that assembly ofsaid system is facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in further detail below with referenceto the accompanying drawings, in which:

FIG. 1A is a sectional view showing a gasket mounted in a seat of a pipecoupling according to an embodiment of the invention.

FIG. 1B is a detail view of the gasket within FIG. 1.

FIG. 2 is an enlarged, sectional view of the gasket in FIGS. 1A-B.

FIG. 3 is an enlarged, sectional view of the seat in FIGS. 1A-B.

FIGS. 4A and 4B are side projections showing two different gasket shapesfor joining pipes of matching shape.

FIG. 5A is a sectional view showing a gasket mounted in a seat of apump-housing coupling according to another embodiment of the invention.

FIG. 5B is a detail view of the gasket within FIG. 5A.

FIG. 6A is a sectional view showing a gasket mounted in a shaft-mountedelement for radially sealing the shaft and shaft mounted elementassembly.

FIG. 6B is a detail view of the gasket within FIG. 6A.

DETAILED DESCRIPTION

A gasket 1, in the present embodiment in the form of a form ring orsealing ring, and seat 2 of an embodiment of the present invention canbe seen in FIGS. 1A and B arranged in a conventional flange couplingjoining two pipes 3, 4, with axially aligned pipes having radiallyextending flanges.

An enlarged view of the gasket 1 is shown in section in FIG. 2. Thegasket is made up of two main portions, where an inner portion 10expands towards the pipe interior at a slight angle and an outer portion11 extends axially, to the left in FIG. 2, forming radial end walls 12,13. These walls 12, 13 preferably form an angle with a longitudinal axisA of the pipe to be sealed. A generally axial groove 14 is formed in theouter portion 11, between the radial end walls 12, 13, substantiallydividing the outer portion 11 into two hinged halves. The angle betweenthe groove walls or the groove angle is larger than the sum of theangles between the radial end walls 12, 13 and the longitudinal axis A.On either side of the groove 14 are walls 15, 16, which are parallel toa flange plane F. The walls 15, 16 are at their distal ends joined tothe outer 12 and inner 13 radial end walls respectively by a radius R ofgenerally equal size. An innermost surface 17 facing the pipe interioris parallel to the longitudinal axis A. An angled wall 18 connects theinnermost wall 17 with the inner radial end wall 13. The right sidesurface 19 is planar and lies in the flange plane F.

In FIG. 3 a matching seat 2 is shown for mounting the gasket 1 of thepresent invention. A flange wall 21 is part of the flange for joiningtwo pipes and this wall 21 lies in the flange plane F. The seat 2further has two walls substantially parallel to the axis A, namely anouter seat wall 22 and an inner seat wall 23, respectively. These walls22, 23 are connected by a wall 24 being substantially perpendicular tosaid walls 22 and 23. The connections between these walls are formedwith a radius R of generally equal size, matching those of the gasket 1.A wall 25 is formed between the inner seat wall 23 and a pipe innersurface 26. This wall 25 is offset to the left from the flange plane Fand further forms an angle with the flange plane.

When the gasket 1 of FIG. 2 is fitted in the seat 2 of FIG. 3, theradial end walls 12, 13 are compressed towards the groove 14 formed inthe center of the gasket outer portion 11. The groove volume is thusreduced but the groove is not completely compressed, since the groovevolume is larger than the sum of the displaced volumes of the radial endwalls 12, 13. This compression of the radial end walls 12, 13 ensuresthat the gasket 1 remains in the seat 2 during assembly of the pipecoupling. The inner portion 10, with the angled wall 18, abuts theslanted inner wall 25 where the inner portion is slightly thicker thanthe offset between the wall 25 and the flange plane F. This means thatthe inner portion 11 is compressed slightly during assembly of the pipesand this improves the sealing ability of the gasket 1. The innermostsurface of the gasket 17 is now aligned with the inner surface 26 of thepipe. A right side surface 19 of the gasket 1 is aligned with the flangeplane F, at least after assembly, and this means that no machining isnecessary in the right hand flange.

When the gasket 1 and seat 2 of the above description are subjected toheat, they will expand. However, the thermal expansion of rubber isabout seven times as high as that of metal. Therefore, the groove 14 ofthe gasket's 1 outer portion 11 allows for compensation of thisexpansion difference and this minimizes the expansion of the gasket 1 tothe interior of the pipe. The main purpose of groove 14, when the gasket1 is assembled in the flange 3 is to compensate for this expansionduring thermal changes. Furthermore, the expansion of the gasket innerportion 10 is reduced due to its small size.

An increased pressure in the pipe will lead to an increased sealingpressure of the gasket 1, both axially and radially, since the inwardlyexpanding inner portion 10 is self-engaging. The pressure against theinnermost surface 17 will force the inner portion 10 inwards increasingthe pressure between the angled walls 18 and 25, thus improving thesealing ability. Hence, such a pressure applied onto the gasket improvesthe sealing capability of the gasket 1 and seat 2 system by tighteningthe gasket 2 using the hydraulic force caused by the pressure andpressing the gasket tighter into its counter sealing surface forimproved sealing of the gasket against the counter faces. The inwardlyexpanding inner portion further reduces the tendency of outward radialdisplacement towards the outer portion, caused by an increased pressurein the pipe. The above gasket 1 now seals the flange coupling withoutpresenting any cracks, crevices or protrusions to the interior of thepipe.

The gasket of the present invention may, as mentioned above, be mountedin a hollow joint, such as a pipe flange coupling, only requiringmachining in one side of the flange surfaces. The gasket is furtherself-retaining, which simplifies assembly. This is both cost- andtime-effective. Moreover, the gasket provides a way of sealing twopipes, or similar couplings such as two joined elements of pumphousings, without presenting any edges or cracks to the interior of thepipe or the coupling, even if the temperature is increased to about 140C.

The gasket of the present invention may be manufactured from differentkinds of polymeric material having elastic and resilientcharacteristics, e.g. rubber materials such as EPDM, Viton®, VMQ, FPM,FKM and HNBR, thermoplastic materials, or compositions comprising suchmaterials singly or in combination. Care should be taken so the chosenmaterial does not affect the contents in the pipe. If desired, thegasket may be provided with further advantageous properties, forinstance it may be covered with a suitable coating, e.g. a silver ioncoating if the gasket is to be antiseptic. Further, such materials ase.g. silver ions may be homogenously distributed in the gasket materialin order to provide the desired properties. This is advantageouslyachieved by mixing such additives into the gasket material or by coatingthe gasket prior to forming and curing the same or by coating the gasketprior to curing the polymeric material. The right hand surface 19 of thegasket 1 is illustrated as being planar, but this is not necessary. If acertain compression of the rubber is wanted, this may be achieved byincorporating a specific profile in this surface 19, which though willbe planar after assembly, so that machining of only one part of thecoupling for fitting the gasket is necessary.

The overall shape of the gasket is determined by the shape of the joint,e.g. a pipe coupling, and the gasket will be formed to follow theinterior surface of the pipe. In FIGS. 4A and 4B, two different gasketshapes 40, 41 are shown as non-limiting examples.

The gasket and seat system of the present invention is shown in a pipecoupling with parallel interior walls, but may just as well be mountedin conical couplings or joints. It may be used in flange couplings,housings of pumps (see example below), pipe fittings, tube fittings,pipe couplings, and/or union couplings. It may also be used for dairyfittings, joined houses, e.g. of a pump, mechanical sealings, or similaras is evident to a person skilled in the art. The gasket and seat systemof the present invention may also be used in heat exchangers, especiallyin the food and pharmaceutical industry. Non-limiting examples of pumphousings are for instance a housing of an eccentric screw pump, whichmay use a gasket as shown to the right in FIG. 4, or a twin screw pump(see FIGS. 5A and 5B), which may use a gasket having the shape as shownto the left in FIG. 4, for displacement of viscous fluids, such as food.The pump housing 50 is generally built in a pipe system for transportingthe fluids therein, e.g. milk products. More precisely, with referenceto FIGS. 5A and 5B, the pump housing 50 may comprise a flange coupling51 to a pipe feeding in the fluid 55 to the pump, as well as a furtherflange coupling 54 on the other ending of the pump housing, to a pipe ora driving unit 53 for the twin screws 52, into which the pump displacesthe fluid fed in from the feeding pipe. Hence, the gasket and seatsystem may also be located in such a joint having pipe to pump couplingsas elements, as described above.

The gasket and seat system may also be arranged in a housing 60, forsealing off e.g. a shaft 61 having mounted thereon a shaft mountedelement, see FIGS. 6A and 6B. In rotation of the shaft 61, element 60rotates together with the shaft onto which it is mounted. However,element 61 is attached to shaft 60 in such a manner that it may move apredefined short distance in axial direction. Even in this case, thegasket 62 will ensure sealing according to the above given conditionsconcerning hygienic sealing and pressure durability. More precisely, inthis case, the wall 17 facing the interior of the housing is angled awayfrom a common point of engagement for the interior surface 26 and thewall 17. This increases the angle in the corner in order to preventproduct from being retained in that area. The gasket 62 has also aninner and outer portion, as gasket 1, and a radial groove 63, which iseasily perceivable from FIG. 6B. An axial movement of element 60 over ashort distance in relation to shaft 61 is possible without degradationof the sealing capabilities of gasket 62. The gasket 62 may for instancebe a radial sealing ring, shaft 61 and the element mounted thereon maybe a shaft in a pump. As mentioned above, the gasket may beself-retaining inside the seat, which simplifies the procedure ofcoupling the joint elements, e.g. pipes or union elements. Hence, amethod of assembly a gasket and seat system is provided by the presentinvention, for sealing a joint of elements as described above. Themethod comprises the step of pre-mounting the gasket in one element ofsaid joint that comprises the seat for the gasket. In this way theassembly of the system is facilitated, compared conventional gaskets,such as O-ring sealings that are not self-retaining and cause acomplicated and expensive assembly of such systems.

Equivalent elements can be substituted for the ones set forth above suchthat they perform in substantially the same manner in substantially thesame way for achieving substantially the same result.

It is believed that the system and method as described and many of itsattendant advantages will be understood by the foregoing description. Itis also believed that it will be apparent that various changes may bemade in the form, construction and arrangement of the components thereofwithout departing from the scope and spirit of the invention or withoutsacrificing all of its material advantages. The form herein beforedescribed being merely exemplary and explanatory embodiment thereof. Itis the intention of the following claims to encompass and include suchchanges.

What is claimed is:
 1. A gasket and seat system suitable for sealing ajoint, wherein the gasket is made of a polymeric material, said gasketcomprising: an inner portion having a wall forming an inner diameter ofthe gasket, the wall in contact with an interior and high pressure sideof the joint, and an outer portion, arranged radially outside said innerportion, and said outer portion extends axially forming radial endwalls, wherein the gasket is formed with a groove in the outer portionbetween said radial end walls, wherein said radial end walls arecompressible towards the groove for fitting into said seat.
 2. Thegasket and seat system according to claim 1, wherein the wall facing theinterior of the joint is adapted to be flush with an interior surface ofthe joint when mounted in the seat.
 3. The gasket and seat systemaccording to claim 1, wherein the wall is angled slightly inwards from acommon point of engagement for an interior surface.
 4. The gasket andseat system according to claim 1, wherein the inner portion of thegasket is formed with an angled wall connected at the wall and at one ofthe radial end walls so that the wall and angled wall are contiguoussurfaces forming an angle, whereby the inner portion increases inbreadth from the outer portion to the wall in contact with the interiorand high pressure side along the angled wall, wherein the angled wallparallels a matching angled wall of the seat.
 5. The gasket and seatsystem according to claim 1, wherein the gasket is formed with angledwalls of the outer portion which are compressed upon entry in the seat.6. The gasket and seat system according to claim 1, wherein a gasketsurface facing a flange plane is adapted to be flush with the flangeplane after assembly.
 7. The gasket and seat system according to claim1, wherein the gasket comprises silver ions, in order to obtainantiseptic properties.
 8. The gasket and seat system according to claim1, wherein said joint is a pipe coupling.
 9. The gasket and seat systemaccording to claim 8, wherein said pipe coupling comprises two flanges,wherein the gasket is located in one of said flanges only, preferablypre-mounted in said one flange during assembly of said system.
 10. Thegasket and seat system according to claim 1, wherein said joint isinstalled in a pump housing of a pump for food processing orpharmaceutical product processing.
 11. A gasket of polymeric materialadapted to seal a joint, said gasket comprising: an inner portion with awall forming an inner diameter of the gasket, wherein the wall is incontact with an interior and a high pressure side of said joint when inuse, and an outer portion, which extends axially forming radial endwalls, wherein the inner portion of the gasket is formed with an angledwall connected at the wall and at one of the radial end walls such thatthe wall and the angled wall are contiguous surfaces forming an angle,whereby the inner portion increases in breadth from the outer portion tothe wall in contact with the high pressure side.
 12. A gasket ofpolymeric material adapted to seal a joint, said gasket comprising aninner portion, with a wall forming an inner diameter of the gasket,wherein the wall is in contact with an interior and a high pressure sideof said joint when in use, and an outer portion, which extends axiallyforming radial end walls, and wherein the outer portion comprises agroove between the radial end walls, wherein said radial end walls arecompressible towards the groove for fitting into a seat.